Furnace.



E. SIEMENS.

PURNAGE.

APPLICATION FILED 1111111.18. 1910'.

Patented Feb. 13, 1912.

INVENTOPM WITNESS ES'.

FRIEDRICH SIEMENS, 0F BERLIN, GERMANY.

FUBNACE.

Specification of Letters Patent.

Patented Feb. 13, 1912 yApplication filed March 18, 1910. Serial No. 550,212.

To all lwhom t may concern.'

Be it known that I, FRIEDRICH SIEMENS, a subject of the German Emperor, and residing at Berlin, Germany, have invented cert-aln new and useful Improvements 1n Furnaces, of which the following is a specification.

My invention relates to regenerative continuous furnaces for metallurgicall purposes, and to 'cement rotary-furnaces, calcining furnaces, and the like.

The former modes of employing the regenerative principle in connection with continuous furnaces for metallurgical purposes, cement rotary-furnaces, calcining furnaces and 'the like suffered from certain defects which will now be described with reference to a regenerative continuous furnace for metallurgical purposes The air for combustion could not be highly heated to at least 900o C., at which temperature the wellknown advantages of regenerative gas-ring ir'st become evident, in 'the construction of continuous furnaces for metallurgical purposes well-known heretofore, on the one hand'because the burned gases to be utilized for pre-heating the air for combustion were too much cooled by iowing over cold ingots and, on the other hand, because the products of combustion had to be taken oif at the ends of the longpushing bed, so that, on account of the charging door which is located at this place and is alrnost alwaysopen in a large furnaceLcold air was drawn into the discharge iues of the products of coinbustion which, again, materiallyimpaired the regenerating capability of the burned gases. Further, in continuous furnaces, known heretofore, whether according to the regenerative gas, recuperative gas, half gas' or direct-cV red system, the consumption by burning ofthe ingots was relatively increased by the flame, which impinged according to the counter-current principle on the most highly heated ingots, having to carry with it an excess of air, on the one hand in order to obtain the desired high temperature, and on the other hand to enable complete combustion of the entire quantity of gas over the entire length of the .heating and finishing chambers. But precisely at this place itis of the greatest importance that an excess of air for combustion beavoided, both because the ingots already highly heated at this lace oxidize particularly readily, and also.

ecause the air and gas directly behind the pinge on the hot ingots. Again, in the known makes of continuous furnaces, above all in those provided wlth regeneration or recuperation, it is exceedingly difficult to supply the sufficient quantity of air to the fiame, because the charging door which' is generally open allows atmospheric air to pass into the discharge flues and diminishes the draft of the furnace. Therefore it has been necessary heretofore to supply compressed air.

It has been proposed heretofore, in addition, to divide the continuous furnace int-o two parts, namely into the inishin chamber and the heatingchamber, of which each was to be provided with a special furnace. But it is obviously not possible to work the heating chamber with a regenerative furnace because a reversal of the direction of the flames is not possible here, since such reversal would cause the ingots which` have just arrived into the heating chamber to be temporarily impinged by the hot flame, while the ingots approaching the finishing chamber would have to be flowed over by the colder portions of the flame. On the other hand, the regenerative furnace of the finishing chamber is not suiliciently utilized. As the ingots are already heated to bright red heat as they enter into the finishing chamber,

the llame in this part of the continuous fur- I nace will have relatively little opportunity of giving up heatv to the ingots. Therefore the flame will enter with the greatest portion of its heat into the regenerator chamber. On the other hand, thanks to lthe air being highly pre-heated, the finishing chamber will be able to work with'eJ less quantity of air, so that consequently the air-for combustion would take up only a small quantity' ofl the heat stored in the regenerator 'cham ers and therefore the burned gases would esca e at a higher temperature into the smoke stac In addition, when exclusively the air for combustion is preheated and the gas is employed at its temperature of production, as is generally the case at the present day, the quantity -of gas (burned gases) giving oil' heat ismore considerable initself than the quantity (air for combustion) taking up lheat. Thus when a regenerative furnace is' usedcfor the finishing chamber an kexcess .of heat must resllt." p

The same or. similar defects' arepmet l,with

in cement rotary-furnaces, calcining furnaces and similar makes of furnaces, particularly in allf'urnaces, in which as large a fall of temperature as possible is to be obtained on a grate extended at full length as short as possible from the one end to the other, so that any material which is to be heated on the counter-current principle can be moved through the furnace from the cold charging' end to its hottest discharging end. All these furnaces can be divided into two parts as in continuous furnaces, of which parts that located at the discharging end must have the highest temperature, while the other beginning with the charging end must have a gradually increasing, but fairly low, initial temperature.

My invention substantially consists in heating these two parts of the furnace differently by utilizing the heat of the part heated most highly for 'heating the other part which is to be heated less highly; this can be effected e. g. in a continuous furnace and a finishing furnace by using the excess heatof the regenerative furnace of theniahing chamber for the heating chamber. This idea, on which my invention is based, can be embodied in various forms in continuous furnaces and in finishing furnaces; by means of a cooled reversing valve, ll can use directly pre-,heated air'from the regenyerators for feeding the flame in the heating chamber and conduct it to the Aburner heads in the heating chamber. Special channels or recuperators may be built into the regenerators of the finishing chamber',

however, through .which the air for com-4 bustion necessary for the heating chamber flame fiows and is heated tothe requisite temperature. The gas for the flame in the heating chamber ism this event taken' from the producers of the finishing chamber.

My invention can also be carried into practice, however, by draw-ing away one portion of the flame of the finishing chamber linto the heating chamber and consequently working this with a portion of the finishing chamber liame. ance of temperaturein the regenerativefu'r-` naceis guaranteed by only one portion of the flame Howing through the regenerators, while the other portion heats the heating chamber.' rlhis form of my invention is preferable, above all, for small makes .of furnaces, thus Where specialheating of the heatingchamber with burner heads speciallyq provided therefor is done away with. It may, however, be combined in large furnaces with the previously described forms-and be vemployed in such manner that, when .the furnace is heavily loaded, the special means for heating the heating chamber are operated; if there is but littlel work, however, these special heating means are cutoli' and a portion of the finishing chamber liame is sucked through the heating chamber. Lastly, ll can In this event the balcombine these different forms of my invention by supplying only a small quantity of gas and highly heated air for combustion to the heating chamber, and simultaneously drawing ofa small portion of the finishing chamber flame through the heating `chamber. In all these cases the balance of tem. i

re uisite heat, in order to enable the flame to e guided as required.

Une illustrative embodiment of my 1nvention as applied to a continuous furnace comprising a heating and fnishin chambery is illustrated by way of example 1n the acv companying drawin wherein Figure 1 is a vertlcal longitudinal section through the continuous furnace on the line 1-1 of Fig. 2, and Fig. 2 is a horizontal section through the same on the line 2-2 of Fig. l.

Referring to thedrawing, the continuous furnace is divided by the partition wall A into .two parts, namely the finishing chamber A1 and the heating chamber A2. This division can also beeffected by bringing the arch correspondingly lower; further, the finishing chamber may remain not separated from the heating chamber when itis possible exactly to regulate the pressure and draft conditions in the furnace.

The finishing chamber, in which there is to be a high welding temperature, excess of air for combustion being avoided as much as possible, is heated by` a regenerative gas flame. The gas .is produced in the producer shafts B in immediate proximity to `the bed and after passing a gas valve C op erated from one side only passes into one of the two Hues or gas here'meets wit the highly heated air passages D and E. The

for combustion which has entered through an ordinary air valve F and has flowed into one of the regenerators'G, d. By reversing the valvesv F and-U thewell-known regg y1 erative principle comes hito action. regulating the smoke-,stack draft and the vgas-pressure it is possi-ble to regulate the dame and limit ittothe'jnishing chamber..

ber is brought by a branch L from t e producers to the burner heads M and to the v dues` or assages. rlhe air for combustion for the eating chamber is pre-heated in the illustrative embodiment in channels or recuperators K built into the .regenerators G and J. As previously mentioned, it is also possible to supply a portion of the air for combustion heated in these regenerators directly to the burner heads M for feeding the iiame in the heating chamber.

In the case of small furnaces, as stated above, the special means for heating the heating chamber will not be necessary. The heating chamber is heated, as indicated above, by regulating the smoke-stack draft and the gas-pressure and drawing oit a portion of the finishing chamber iame so that this portion of the flame can flow through the heating chamber.

The Haine in the heating chamber is utilized owing to the greater length of the chamber. Recuperation of the burned gases which esca e atN and O is unsuitable, on the one hand because the pre-heated air for the heating chamber must be heated higher than the temperature of the burned gases, and on the other hand because without recuperation of the burned gases of the heating chamber the charging door can be left open without the recovery of the burned gases being rendered difficult. The flame in the heating chamber is regulated by dampers arranged at the burner heads M. The two smoke-stack flues P and Q, are provided with separate dampers but preferably open into the same smoke-stack.

As mentioned above, in the arrangement illustrated in the drawing several forms of my invention can be used and combined one with another. Thus it is possible entirely to close the burner heads M and to work the heating chamber A2 by means of a portion of the finishing chamber flame which is drawn into the heating chamber. The burner heads M may, however, be partially ope-n so that a certain quantity of gas and air flows in. a portion of the finishing chamber flair-s being simultaneously drawn oif into the heating chamber.

The hereindescribed furnace can thus be worked in the most various ways according to the requirements at any time.

` vMyinvention can be applied construc` tively to other kinds of furnaces, as e. g. cement rotary-furnaces, calcining furnaces etc. in an exactly analogous manner, for which reason the same have not been represented on the drawing, and it is, of course, to be understood that the term furnace as used in the claims is to be considered in its broad sense.

1. In an apparatus of the class described, in combination, a furnace, means for heat ing a portion of said furnace by a reversing flame, and means for drawing oif a portion of said reversing flame to heat another portion of said furnace.

2. In an apparatus of the class described, in combination, a furnace, a regenerator op eratively associated with said furnace, means for heating a portion of said furnace by a reversing flame from said regenerator, and means for drawing off a portion of said reversing flame to heat another portion of said furnace.

3. In an apparatus of the class described, in combination, a furnace comprising a plurality of parts, a gas producer operatively associated with said furnace, a regenerator operatively associated with said furnace and with said gas producer, means 'for delivering heated gases from said producer and said regenerator to one part of said furnace to form a flame, and means for causing a portion of said flame to pass to one of the other parts of said furnace and for causing the remaining portion of the flame to pass into the regenerator.

In testimony whereof, I aiiiX my signature in the presence of two witnesses.

FRIEDRICH SIEMENS.

Witnesses: v

WOLDEMAR HAUPT, HENRY I-IAsPER. 

